How Long Is Stomach Flu Contagious?

The stomach flu is often contagious from the time you're exposed to whatever is causing it. It remains so the whole time you're sick (when you're most contagious) and for quite a while after you start feeling better. Altogether, this can add up to a few weeks.

Exactly how long you are contagious depends on what you're infected with. There are several pathogens that can cause the stomach flu.

This article looks at the various durations for which the stomach flu is contagious and how long you should stay home if you get it.

Stomach Flu Contagiousness by Cause

Some viruses and bacteria that cause the stomach flu, or gastroenteritis, may be contagious for longer or shorter periods than others.

This is because of variations in how long it takes to develop symptoms, how long you have them once you get them, and how long you are contagious after symptoms have resolved.

You may very well pass on the stomach flu to someone else before you even know you have it or well after you think it has passed.

Here's a look at four common causes of the stomach flu and how long they are contagious by stage.

How Long Should You Stay Home With the Stomach Flu?

Follow your healthcare provider's advice on how long you should stay home with the stomach flu.

Generally speaking, those with the stomach flu should stay home for the duration of their illness and between 24 hours and 48 hours after symptoms go away.

Anyone who's running a fever is definitely contagious. Even without a fever, stomach viruses are easy to spread.

You may be tempted to go to work or send your child to school after a night that's free of vomiting or diarrhea. However, it's important to wait a full 24 hours after the last episode.

Though it's possible, symptoms are unlikely to come back if they've been absent for that period.

How Stomach Flu Is Spread

Stomach flu is usually spread by the fecal-oral route—accidental ingestion of infected stool.

This can come from:

• Consuming contaminated food or water
• Touching contaminated objects or surfaces
• Coming into close contact with an infected person

When to Call a Healthcare Provider

While you do what you can to prevent spreading the stomach flu to others, be sure you are also taking care of yourself by resting and hydrating.

Call a healthcare provider or go to your nearest urgent care center if you have the stomach flu and you:

• Cannot keep down fluids for more than 24 hours
• Have a fever over 104 degrees F
• Have been vomiting for more than two days
• Have signs of severe dehydration
• Have bloody stools
• Have bloody vomit

Summary

Stomach viruses are highly contagious. You can spread them before symptoms begin and for up to two weeks after you recover.

It's advisable to stay home for 24 to 48 hours after your vomiting, diarrhea, and fever have gone away to make sure you're symptom-free.

The best way to prevent the spread of stomach flu viruses like norovirus and rotavirus is to wash your hands frequently and isolate yourself when sick.